372 



ö. HAÏTA 



19. în older embryos of Stage in, the visceral layer of the 

 iiephrotome is folded out, and is called the coelomic projection 

 which resembles the coelomic pocket described by Price for 

 Bdellostoiiia ; however, in Bdellostoma, the fold is derived from 

 iliö pariclal and visceral layern of the lateral plate and is after- 

 wards converted into the Bowman's capsule, whereas the coelomic 

 projection is the product of only the elsceral layer of the nephro- 

 toiiie ; it gives rise to the radix of the mesentery which offers 

 materials to the mesonephric tubules and to the gonads. 



20. The topographical position of the pronephros becomes 

 first definite in Stage iv. It is situated in the chest cavity, dorso- 

 lateral to the heart, forward of and dorsal to the liver, extending 

 along either side of the chorda. This position is somewhat 

 changed as the development proceeds ; the pronephros comes, 

 in later stages, in front of the liver. 



21. During Stage iv, a structure, which I have called 

 above the peritoneal partition, is observed as an outgrowth 

 of the peritoneal wall and disappears during the same stage. 



